1. Field of the Invention
This patent application concerns a signalling device, and, more specifically, a device for keeping birds away with differential management functions.
2. Description of the Related Art
Birds represent a serious problem in a variety of environments. For example, in agriculture, birds damage plants and cultivations, in fish-growing farms, birds attack the fish stock, and in airports and other surfaces to be used by airplanes, birds hinder the movement of the airplanes, especially during take-off and landing.
A device for keeping birds away is known and adopted in the prior art, and generally consists of a casing containing a pulse sound and/or light emitter.
Said device in the prior art emits sounds and/or light flashes at regular intervals and is usually positioned in the area that must be protected against birds. Such light and sound emitter operates at regular intervals that are predetermined during the production phase.
This device is not very effective, because birds memorize the time intervals between successive sound or light signals, entering the area protected by one of these devices after a signal and leaving it just before the successive one. Even if the related time interval is changed, after a while the birds memorize the new sequence, thus making the new adjustment useless.
Some devices are adjusted or manufactured to emit sound and/or light signals continuously. These devices are not very effective either, because the birds, after a lapse of time during which they get used to these signals, become insensitive to sound and light emissions.